I'm wandering a little outside of my area of primary interest with this post on possible dietary correlates attached to the risk of psychosis. I therefore tread carefully and hopefully succinctly with this post based on two independent pieces of research recently published by Gracious and colleagues* (full-text) and Karlsson and colleagues**.
Perhaps best to start with a very brief description of what psychosis is and isn't. Psychosis is more of a symptom rather than a stand-alone condition involving a loss of contact with reality where a person is described as not being able to distinguish between what is real and what is imagination. Symptoms include hallucinations, delusions, confused and disturbed thoughts and a lack of insight and self-awareness. I say not a condition in its own right but there had been some discussion in the preparations for DSM-5 to include a new category called 'attenuated psychosis syndrome' which seems to have been dropped from the latest manifestiation. I should also point out that psychosis does not mean psychopath or anything similar.
The causes of psychosis are still the source of some speculation but generally speaking, three main areas have been put forward as reasons for psychosis including: (i) psychotic episodes linked to an underlying mental health conditions such as schizophrenia or bipolar disorder, (ii) episodes linked to more somatic health conditions such as hypoglycemia (low blood sugar) or dementia, and (iii) episodes following the taking of various drugs of abuse or in rare cases, more 'mainstream' pharmacotherapy. These areas are not exhaustive as per the suggestions about stress and social adversity also being risk factors.
The paper by Gracious and colleagues* suggested that vitamin D deficiency and insufficiency seemed to be quite a common occurrence in cases of adolescents presenting with mental health problems, and was particularly marked where psychosis was a feature of the expression of those problems. Their data also suggested that ethnicity and vitamin D levels seemed to be important factors. Similar data based on the examination of adult psychosis has suggested a related connection to the sunshine vitamin and indeed a potential 'protective' effect from adequate vitamin D intake. Takes me back to the whole vitamin D-autism debate acknowledging that autism is not psychosis and psychosis is not autism.
The paper by Karlsson and colleagues** was slightly different insofar as reporting on a possible connection between maternal circulating levels of IgG anti-gliadin antibodies and the presence of non-affective psychosis in offspring. To some degree this work ties into the wheat and schizophrenia link posited by people like the late Curt Dohan and followed up in the recent paper by Emily Severence and colleagues on food antigens and gastrointestinal inflammation in cases of schizophrenia. I'm also reminded of the very interesting work being done by Drs Marios Hadjivassiliou and David Sanders from right here in Blighty on the extra-intestinal manifestations of issues with gluten (see here and here).
Both the Gracious and Karlsson papers caught my eye given that both suggest an association between dietary components and mental health. Before you ask, yes, these were studies of association and let's face it, associations are abound in lots of areas nowadays so some caution needs to be applied. One could also argue that vitamin D whilst partially dietary-derived has a strong link with sunlight exposure and you would of course be right. Having said that don't underestimate how important dietary vitamin D might be especially in places where sunlight, the right kind of sunlight, is not necessarily always at a premium.
Diet potentially mediating behavioural symptom presentation - now where have we heard that before? Accepting that any link between food and mental health is likely to be complicated and influenced by lots of other factors, there are several potentially important points to make from these and other studies not least on how gut biology may very well have an influence on brain and behaviour with diet as an important factor. One does also wonder whether before reaching for the 'treatment' of these symptoms, medical science perhaps needs to have a more detailed look at how we might be able to influence the 'onset' of such symptoms via adequate dietary and nutritional means. Food for the body, food for the mind? (bearing in mind my caveats about not giving medical advice).
To finish, UK viewers might be tuning into The Voice on the BBC. I like Jesse J and will.i.am but lets face it, Sir Tom (Jones) is the main event when it comes to a voice (sorry guys). So here he is with The Stereophonics (he looks much better with grey hair).
* Gracious BL. et al. Vitamin D deficiency and psychotic features in mentally ill adolescents: A cross-sectional study. BMC Psychiatry. May 2012.
** Karlsson H. et al. Maternal antibodies to dietary antigens and risk for nonaffective psychosis in offspring. American Journal of Psychiatry. April 2012.